Do twins run in your family?

One of the most common questions I get when I go out with the kids is “do twins run in your family?” Completely understandable considering the chance of conceiving twins naturally is a bit over 1%. Two sets is statistically very improbably without some natural predisposition towards it.

Twins sort of run in my family, as in there are several sets I’ve heard about. My dad’s mom miscarried a set of twins, some cousin supposedly had two sets of twins and a set of triplets among a family of 12 or so children, and my mom’s dad reportedly was a twin but the twin died either in utero or shortly after birth.

None of that matters though. My twins are from IVF. We’ve transferred two embryos four times and both took the last three times. The only failed transfer was the first, fresh transfer. After the egg retrieval my hormone levels were very hard to control and probably made my body inhospitable for implantation. That may have been a blessing in disguise for my health since I also had mild Ovarian HyperStimulation Syndrome (OHSS).

Embryos from second frozen transfer

My reproductive endocrinologist (RE) said that for each two-embryo transfer, I’d have approximately a 25% chance of twins, 50% chance of a singleton, and 25% chance of no pregnancy. Somewhere in there was also a 1%-2% chance of triplets or more (one or more embryos divides). If those number are correct, three sets of twins in a row carries a 1.6% chance.

Also, almost 60% of twins are born preterm (before 37 weeks), according to the American Pregnancy Association. (This includes fraternal and identical and identical are often higher risk and are evicted earlier.) Both of my sets so far were evicted as late as the doctor would allow, about 38.5 weeks, and this third set is on track to do the same. They’ve all weighed between 5 pounds 15 ounces and 6 pounds 6 ounces, so no low birth weight babies either.

This is a perfect case study of how statistics apply to a large population, not to an individual. Neither I nor any of my kids have faced complications related to multiple births. You could say I’m lucky. I think I am. My body happens to handle twin pregnancies well and it seems to respond very well to the IVF protocol we use.

We have 8 frozen embryos left out of 16 embryos from a single egg retrieval procedure. The doctor retrieved 42 eggs, I think, which is an unusually high number. According to my RE’s website, the average number of eggs retrieved in my demographic is 10.3. Of those, 2.6 become day-5 blastocysts–the earliest stage at which they can be frozen. The survival rate to that point is about 27%. Our survival rate was 38% (16/42). As I said, IVF worked particularly well for me/us.

The RE apologized for such high numbers. That’s remarkable because he usually comes across as very self assured and he is certainly very good at what he does. In his apology, his tone was almost one of failure. He failed to control the process as well as he wanted and as well as he usually does. He aims for far fewer eggs since more eggs means higher risk for the woman and more embryos can result in some difficult decisions for the parents.

Jeff and I have talked about what to do with all the embryos and have our plan in place. I’ll talk about that in a separate post. For now, I’ll say that having the first set of twins completely changed my perspective.